MAXI J1659-152 - UvA-DARE
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
space telescope imaging spectrograph survey of far
... and an absolute wavelength calibration compared with using the Chandra or XMM-Newton grating spectrometers to observe permitted transitions of the same ion stages in the kilovolt X-ray region. Fe xii 1242, 1349 (T 2 106 K) and Fe xxi 1354 (107 K) are well known from solar studies and have bee ...
... and an absolute wavelength calibration compared with using the Chandra or XMM-Newton grating spectrometers to observe permitted transitions of the same ion stages in the kilovolt X-ray region. Fe xii 1242, 1349 (T 2 106 K) and Fe xxi 1354 (107 K) are well known from solar studies and have bee ...
doctoral thesis (Dissertation)
... are required to explain the observed spectrum. For a electron density > 105 cm−3 all shock dimensions are so small that they remain undetectable in optical observations as observed. The spectral resolution in X-rays is not sufficient to analyse the line profiles, so UV data is used for this purpose. ...
... are required to explain the observed spectrum. For a electron density > 105 cm−3 all shock dimensions are so small that they remain undetectable in optical observations as observed. The spectral resolution in X-rays is not sufficient to analyse the line profiles, so UV data is used for this purpose. ...
Neutron stars: the densest state of condensed matter
... discovered by James Chadwick. He was awarded the Nobel prize in 1935. Talk of D. G. Yakovlev from Ioffe Institute in St Perterburg ...
... discovered by James Chadwick. He was awarded the Nobel prize in 1935. Talk of D. G. Yakovlev from Ioffe Institute in St Perterburg ...
MAXI J1659-152: The shortest orbital period black
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
Astronomy 305/Frontiers in Astronomy - Fermi Gamma
... NS spin period seen in bursts ~5-10 sec, shows evidence of rapid spin down No orbital periods – not in binaries! 4 well studied systems + several other candidate systems Several SGRs are located in or near SNRs Soft gamma ray bursts are from magnetic reconnection/flaring like giant solar flares Lx = ...
... NS spin period seen in bursts ~5-10 sec, shows evidence of rapid spin down No orbital periods – not in binaries! 4 well studied systems + several other candidate systems Several SGRs are located in or near SNRs Soft gamma ray bursts are from magnetic reconnection/flaring like giant solar flares Lx = ...
MAXI J1659−152: the shortest orbital period black
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
... weeks into the outbursts, again drops in intensity are seen. These dips have, however, a spectral behaviour opposite to that of the absorption dips, and are related to fast spectral state changes (hence referred to as transition dips). The absorption dips recur with a period of 2.414 ± 0.005 h, whic ...
Fundamental properties of Ana González Galán
... The aim of this thesis is to characterise a sample of High Mass X-ray Binaries (HMXBs) formed by: IGR J00370+6122, XTE J1855-026, AX J1841.0-0535 and AX J1845.0-0433. These objects are composed of pulsars (rotating neutron stars) accreting material from the wind of their supergiant companions. The X ...
... The aim of this thesis is to characterise a sample of High Mass X-ray Binaries (HMXBs) formed by: IGR J00370+6122, XTE J1855-026, AX J1841.0-0535 and AX J1845.0-0433. These objects are composed of pulsars (rotating neutron stars) accreting material from the wind of their supergiant companions. The X ...
Sample pages 1 PDF
... the compact object the accretion disk is transformed into a hot optically thin and geometrically thick flow with the aspect ratio of H/R∼0.5–1. The soft (optically thick) and hard (optically thin) spectral components are formed in the accretion disk and the hot inner flow correspondingly. The value ...
... the compact object the accretion disk is transformed into a hot optically thin and geometrically thick flow with the aspect ratio of H/R∼0.5–1. The soft (optically thick) and hard (optically thin) spectral components are formed in the accretion disk and the hot inner flow correspondingly. The value ...
VLT observations of GRS 1915+ 105
... several observers at different wavelengths. In spite of this work, the nature of the X-ray binary system in GRS 1915+105 is still a matter of debate. The strong interstellar absorption towards the source, that implies optical extinctions of AV ∼ 27 magnitudes (Chaty et al. 1996), appears as the main ...
... several observers at different wavelengths. In spite of this work, the nature of the X-ray binary system in GRS 1915+105 is still a matter of debate. The strong interstellar absorption towards the source, that implies optical extinctions of AV ∼ 27 magnitudes (Chaty et al. 1996), appears as the main ...
High-mass X-ray Binaries: X-raying the winds Ángel Giménez García
... γ Cassiopeae fue descubierta por Pietro Angelo Sechi en 1867, convirtiéndose en la primera estrella de clase Be. Forma parte de un sistema binario con un periodo orbital de 204 días y baja excentricidad. De la componente secundaria se sabe poco, más allá de que tiene una masa similar a la solar. En ...
... γ Cassiopeae fue descubierta por Pietro Angelo Sechi en 1867, convirtiéndose en la primera estrella de clase Be. Forma parte de un sistema binario con un periodo orbital de 204 días y baja excentricidad. De la componente secundaria se sabe poco, más allá de que tiene una masa similar a la solar. En ...
Neutron Stars and the Determination of the Dense Matter Equation
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
... A physical understanding of the behaviour of cold ultra-dense matter – at and above nuclear density – can only be achieved by the study of neutron stars. The surface thermal emission from neutron stars in quiescent low-mass X-ray binaries (qLMXBs) inside globular clusters has proven useful for that ...
X-Ray Spectroscopy of Stars
... Stars are among the most prominent sources accessible to modern X-ray telescopes. In fact, stars located across almost all regions of a Hertzsprung-Russell diagram have been identified as X-ray sources, with only a few exceptions, most notably A-type stars and the coolest giants of spectral type M. ...
... Stars are among the most prominent sources accessible to modern X-ray telescopes. In fact, stars located across almost all regions of a Hertzsprung-Russell diagram have been identified as X-ray sources, with only a few exceptions, most notably A-type stars and the coolest giants of spectral type M. ...
Absorption of high-energy gamma rays in Cygnus X-3
... Lns ≈ 1033 erg s−1 is too low and will be neglected as well in the following. The dominant source of soft X-rays in Cygnus X-3 is provided by the accretion disk formed around the compact object. The inner parts of the disk could be very hot with temperature T disk ∼ 106 −107 K and emit copious ∼1 ke ...
... Lns ≈ 1033 erg s−1 is too low and will be neglected as well in the following. The dominant source of soft X-rays in Cygnus X-3 is provided by the accretion disk formed around the compact object. The inner parts of the disk could be very hot with temperature T disk ∼ 106 −107 K and emit copious ∼1 ke ...
Five Years of Swift Science: GRBs and More!
... – A very large field of view for finding GRBs & quasars • BREADTH versus Depth for rare objects (Critical) ...
... – A very large field of view for finding GRBs & quasars • BREADTH versus Depth for rare objects (Critical) ...
ASI 2017 Abstract Book - Astronomical Society of India
... Inevitably, the answers to these questions entail a detailed investigation of all the components of the interstellar medium (gas, dust, metals) and their relation to stellar properties, kinematics and environment. This clearly requires multi-wavelength information for statistically significant sampl ...
... Inevitably, the answers to these questions entail a detailed investigation of all the components of the interstellar medium (gas, dust, metals) and their relation to stellar properties, kinematics and environment. This clearly requires multi-wavelength information for statistically significant sampl ...
English version - Richard de Grijs
... A 34-member pulsar study team used the seven-beam receiver of the Arecibo Observatory to conduct routine pulsar searches in what they call the Pulsar Arecibo L-Band Feed Array (or PALFA) Survey. The two recently discovered intermittent pulsars spend most of their time in the OFF state. Three othe ...
... A 34-member pulsar study team used the seven-beam receiver of the Arecibo Observatory to conduct routine pulsar searches in what they call the Pulsar Arecibo L-Band Feed Array (or PALFA) Survey. The two recently discovered intermittent pulsars spend most of their time in the OFF state. Three othe ...
On the possibility of a helium white dwarf donor in the presumed
... the binary. This proposition is supported by detections of orbital periods in two of the other three (18 min in 4U 1543-624, see Wang & Chakrabarty 2004; 21 min in 4U 1850-087, see Homer et al. 1996), although those detections need corroboration since they were made only once in each case. Recently, ...
... the binary. This proposition is supported by detections of orbital periods in two of the other three (18 min in 4U 1543-624, see Wang & Chakrabarty 2004; 21 min in 4U 1850-087, see Homer et al. 1996), although those detections need corroboration since they were made only once in each case. Recently, ...
THE LUMINOSITY FUNCTION OF X
... emission, to these various types of obscured AGNs. Over more than two decades, X-ray surveys have been improving and extending the known AGN luminosity function by including sources at low luminosity, with or without optical emission lines, and hidden by a dense obscuring medium. The Extended Medium ...
... emission, to these various types of obscured AGNs. Over more than two decades, X-ray surveys have been improving and extending the known AGN luminosity function by including sources at low luminosity, with or without optical emission lines, and hidden by a dense obscuring medium. The Extended Medium ...
Telescopes - UMass Astronomy
... smears images over several arc-seconds ⇒ seeing Best sites: 0.5-1 arc second Atmospheric seeing limits the angular resolution of ground-based optical telescopes Solutions: 1. Put telescope in Earth orbit (hard, $$$) 2. Adaptively bend mirror to compensate for atmospheric motions (hard, $$$) ...
... smears images over several arc-seconds ⇒ seeing Best sites: 0.5-1 arc second Atmospheric seeing limits the angular resolution of ground-based optical telescopes Solutions: 1. Put telescope in Earth orbit (hard, $$$) 2. Adaptively bend mirror to compensate for atmospheric motions (hard, $$$) ...
Chapter 4 On the possibility of a helium white dwarf donor in the
... in the flash fuel. The question is: where does the hydrogen and helium come from if not from the donor star? The problem is more severe for hydrogen than for helium because in an evolved donor star like in an ultracompact system the hydrogen can reside only in the outer layers that were lost being o ...
... in the flash fuel. The question is: where does the hydrogen and helium come from if not from the donor star? The problem is more severe for hydrogen than for helium because in an evolved donor star like in an ultracompact system the hydrogen can reside only in the outer layers that were lost being o ...
What caused the GeV flare of PSR B1259-63?
... with the circumstellar material from the companion star, resulting in a small-scale pulsar wind nebula. Weak gamma-ray emission was detected by the Fermi/LAT at the last periastron passage, unexpectedly followed 30 days later by a strong flare, limited to the GeV band, during which the luminosity ne ...
... with the circumstellar material from the companion star, resulting in a small-scale pulsar wind nebula. Weak gamma-ray emission was detected by the Fermi/LAT at the last periastron passage, unexpectedly followed 30 days later by a strong flare, limited to the GeV band, during which the luminosity ne ...
SGR 1900+14
... Radiate covering most of the electromagnetic spectrum Rotate with periods that span five decades (ms to a few hours). Are powered by their own rotational energy, residual surface heat or accretion Live tens of millions of years ...
... Radiate covering most of the electromagnetic spectrum Rotate with periods that span five decades (ms to a few hours). Are powered by their own rotational energy, residual surface heat or accretion Live tens of millions of years ...
ATLASGAL -- The APEX telescope large area survey of the galaxy at
... Received 22 December 2008 / Accepted 20 February 2009 ABSTRACT ...
... Received 22 December 2008 / Accepted 20 February 2009 ABSTRACT ...
History of X-ray astronomy
The history of X-ray astronomy begins in the 1920s, with interest in short wave communications for the U.S. Navy. This was soon followed by extensive study of the earth's ionosphere. By 1927, interest in the detection of X-ray and ultraviolet (UV) radiation at high altitudes inspired researchers to launch Goddard's rockets into the upper atmosphere to support theoretical studies and data gathering. The first successful rocket flight equipped with instrumentation able to detect solar ultraviolet radiation occurred in 1946. X-ray solar studies began in 1949. By 1973 a solar instrument package orbited on Skylab providing significant solar data.In 1965 the Goddard Space Flight Center program in X-ray astronomy was initiated with a series of balloon-borne experiments. In the 1970s this was followed by high altitude sounding rocket experiments, and that was followed by orbiting (satellite) observatories.The first rocket flight to successfully detect a cosmic source of X-ray emission was launched in 1962 by a group at American Science and Engineering (AS&E).X-ray wavelengths reveal information about the bodies (sources) that emit them.